Freeze-drying (e.g., lyophilization, cryodesiccation) is a process to remove water and/or other solvents from products. Freeze-drying has many applications such as preserving a perishable material, making a material more convenient for transport, making of ceramics, producing a product that has a short reconstitution time with acceptable potency levels, and so forth. Freeze-drying can be used for many different materials, including, but not limited to, food, pharmaceuticals, and biological specimens.
In a typical freeze-drying process, the sample, or vials or containers containing the sample, are loaded on temperature-controlled shelves within a chamber and cooled to low temperatures until completely solidified. The freeze-drying chamber pressure is then reduced and the shelf temperature is adjusted to enable removal of the frozen solvent (i.e., drying) via sublimation in a step referred to as “primary drying.” When sublimation is complete, the shelf temperature is raised during a “secondary drying” step to remove additional un-frozen solvent bound to the solid product by e.g. adsorption. When sufficient solvent is removed, the drying process is concluded. If the sample was contained in vials or containers, the vials or containers are then sealed, typically under a sub-ambient pressure of inert gas.